Microprocessors are one of the most versatile electronic devices used by engineers. Typically, a microprocessor is able to recognize and execute a predetermined set of instructions (e.g., add, compare, subtract, jump, etc.). Engineers can direct a microprocessor to handle different tasks by writing different computer programs using the same set of instructions. As a result, different types of products can use the same microprocessor by changing the associated computer programs.
A microprocessor is typically used with a number of peripheral integrated circuit (IC) devices (such as serial interface, parallel input-output device, interrupt controller, disk drive controller, etc.). In many cases, a microprocessor manufacturer supplies a family of peripheral ICs that works best with its microprocessors. Because microprocessors are used in many types of products, these peripheral ICs also need to be flexible enough to be used in many types of products. This flexibility comes with a price: it is more difficult to use the peripheral ICs and the cost of the extra registers, logic, memory, etc. required to make the peripheral flexible, increases the cost of the peripheral. Another reality of casting peripherals into silicon is that it is extremely difficult to anticipate future changes to standards. If such “future” standards could be incorporated into a peripheral, the value of the peripheral would be greatly enhanced.